I have a 70's era 5' American Standard cast iron tub with a right hand drain. While moving the plumbing to the right hand wall, the original installation was with the water supply in the left wall, I discovered that tub is being supported by the front lip and one support foot on the back wall side. The two support feet on the front side of the tub are about 1/2 inch off the subfloor. The back foot is starting to dig into the particle board subfloor. My question, should the original installation have had the subfloor built up underneath the tub so that all the support feet were touching? Would now be the time to jack the tub up and get the subfloor built up to the proper height? I think I can get it in in three 9 inch strips.

Hi Evill:

A cast iron tub will have the front apron on the floor (if floor is level) and the back will be supported via a LEDGER STRIP (4'6" piece of 2"x4") nailed to the wall. I screw my ledger strip first and confirm all is level before pulling tub forward and nailing permanently...just in case I missed by measure...;)

Take some basic measurements where the "feet" will end up and then take some electrical cover plates (4"x4"flat metal plates) and place them where the feet will end up.

Lower the tub onto the ledger strip and check tub for exact level all directions (front to back and side to side)... install more metal shims (cover plates) if needed.

The metal shims assure that the tub legs can never penetrate the particle board floor (poor choice for bathroom subfloor) and the ledger strip assures that the back wall cannot fall... ;)

Hope that helped...

MARK